This invention relates to a watercraft and more particularly to an improved watercraft of a type that does not have its own propulsion unit and which is formed with a berthing area that is adapted to receive a smaller propelled watercraft and be propelled by that watercraft.
There is disclosed in the co-pending application entitled "Watercraft", U.S. application Ser. No. 722,599, filed Jun. 27, 1991 in which I am a co-inventor with Noboru Kobayashi, which application is assigned to the Assignee hereof, a type of watercraft as has generally described in the proceeding paragraph. This type of watercraft provides a large unpropelled hull that has a rider's area that is adapted to seat a large number of passengers. The watercraft is formed with a berthing area into which a smaller watercraft, normally one of the jet propelled type, is adapted to be positioned and which permits the larger hull to be powered by this small watercraft. The seating and control arrangement of the larger watercraft is such that the watercraft may be controlled by operating the controls of the smaller watercraft. There are a number of advantages to this type of watercraft, as described in the aforenoted co-pending application and this application relates to several improvements in that type of watercraft.
As disclosed in the aforenoted co-pending application, a berthing area is provided at the rear central portion of the main hull into which a smaller jet propelled watercraft is docked for propelling the larger unpowered hull. The berthing area is defined in all embodiments of that application by a lower wall in which an opening is formed which opening registers with the water inlet opening of the jet propulsion unit of the smaller watercraft so that the smaller watercraft can power the larger watercraft. As also is disclosed in that application, it is extremely desireable to provide a good seal between the water inlet opening of the lower wall of the main hull and that of the smaller watercraft to insure good efficiency of the propulsion unit.
However, the use of complimentary openings in the lower wall of the main hull and in the small watercraft is not always the most desirable mode of operation. One reason for this is that in many instances different types or different configurations of small watercraft may be placed into the berthing area for powering the larger unpowered hull. In addition, even if the small type of small watercraft is always employed, it will not necessarily insure that the openings in the bottom of the smaller watercraft and in the lower wall will be fully aligned due to docketing differences and also manufacturing variations.
It is, therefore, a principal object to this invention to provide an improved watercraft of this type wherein the opening in the lower wall of the main hull is such that it will cooperate with any of a variety of small watercraft and will insure efficient operation.
As should be somewhat apparent, one way to avoid the difficulties afore referred to is to provide a larger opening in the lower wall of the larger unpowered watercraft. By employing such a larger opening, it will be insured that the smaller watercraft water inlet opening will always register with the opening in the lower wall of the larger unpowered watercraft's berthing area. However, the use of such different size openings presents a number of disadvantages of their own.
For example, when the opening in the lower wall of the berthing area is larger than that of the small watercraft then turbulence may be generated by the water flowing into the jet propulsion unit water inlet opening. This turbulence will adversely affect the efficiency of the smaller watercraft's jet propulsion unit.
It is, therefore, a further object to this invention to provide a water inlet opening configuration in the berthing area of the larger hull that will cooperate with the water inlet opening of the smaller powering watercraft without decreasing the efficiency of the operation of the smaller watercraft.
In conjunction with the configuration of the lower wall of the larger watercraft berthing area and the bottom of the hull of the smaller watercraft, it is important to insure good sealing around the smaller watercraft's lower water inlet opening, as aforenoted. However, even if this area is effectively sealed if other facing areas between the two hulls have uneven configurations and open up air voids, the air in these voids can cause problems and inefficient operation of the jet propulsion unit. Furthermore, it is frequently desirable to configure the underside of the hull of a smaller watercraft with chines or stripes so as to improve the handling of the smaller watercraft. If the larger watercraft lower wall is not complimentary in configuration, the aforenoted problems may exist.
It is, therefore, a still further object to this invention to provide an improved cooperating configuration between the lower wall of the berthing area of the main hull and the underside of the hull of a smaller, powering watercraft.
In the aforenoted co-pending application there are disclosed embodiments that employ winches for pulling the small watercraft into the berthing area of the larger unpowered hull. Although this has some advantages, it may be in many instances be more desirable to provide a simpler configuration without incorporating such a winching arrangement. However, it is also desirable to permit the rider to pull the smaller watercraft into the berthing area without driving it in under power to avoid damaging the hulls of either watercraft.
It is, therefore, a further object to this invention to provide an arrangement which will facilitate a rider in manually moving the smaller watercraft into the berthing area.
It is another object to this invention to provide an arrangement for assisting the rider on the smaller watercraft to draw it into the berthing area without necessitating a winch or the like.
In connection with the mating surfaces between the underside of the hull of the smaller watercraft and the lower wall of the berthing area, it is not always necessary or desirable to provide a close fit in all adjacent areas. However, if there are voids when the two watercraft are joined together air may be trapped in these voids and adversely effect the efficiency of the jet propulsion unit of the smaller watercraft, as aforenoted.
It is, therefore, a still further object to this invention to provide an improved arrangement for the hull configuration of the berthing area that will avoid air being trapped between the lower wall and the hull of the smaller watercraft.
The importance of providing good sealing around the water inlet opening of the smaller watercraft's jet propulsion unit and the berthing area have already been noted. In the aforenoted co-pending application, various hold down arrangements have been described that permit the small watercraft to be held securely into contact with the opening in the lower wall of the main hull. However, the provision of such additional hold downs can incumber the watercraft and add unnecessarily to its expense.
It is, therefore, a still further object to this invention to provide an improved hold down device for a watercraft of this general type.
It is another object of this invention to provide a boarding ladder for a watercraft of this type, which boarding ladder also functions as a hold down for the small watercraft when in the berthing area.
It has been previously noted that it is desirable or, at times, occurs that different small watercraft may be positioned in the berthing area of the larger unpowered hull. There are a number of advantages in being able to accommodate different types of small watercraft in the main hull. However, it is also important to have the small watercraft firmly held in place in the berthing area when it is employed to power the main hull. Any clearances can cause vibrations and other disadvantages result.
It is, therefore, a still further object to this invention to provide an improved arrangement for improving the ability of the main hull to accommodate a wide variety of smaller watercraft and yet hold them firmly in position.